Detecting threatening objects or items such as weapons in public venues has increased in importance as society becomes more violent and the public becomes more concerned with safety. In response to these safety concerns, security screening methods and systems have become more prevalent and are being used in facilities and places where the need for screening was previously not considered necessary. To increase safety while keeping public inconvenience at a minimum, the focus of the security screening industry is to increase the accuracy of distinguishing between threatening and non-threatening objects while maintaining a high throughput.
However, conventional security screening systems (also referred to as “conventional systems”) lack an adequate support structure and capability to combine increased sensitivity with increased selectivity and provide a reasonable throughput. For example, as the sensitivity of conventional systems is increased to facilitate detecting more objects that may be used in a threatening matter, more non-threatening objects are being detected and indicated as threatening objects. Increasing the detection of non-threatening objects adds no benefit to safety and detrimentally decreases throughput, which is very problematic if the conventional system is located in an airport. The conventional systems are detecting watches, belts, pocket change, buckles and keys as being potential weapons, and in response providing “false alarms,” due to a lack of selectivity or distinguishing capabilities of the conventional systems. Accordingly, increased sensitivity without increased selectivity is not beneficial to safety or throughput.
These false alarms, which are due to mischaracterizing non-threatening objects, have a dramatic effect on the throughput of a conventional system as evidenced by the long lines of people awaiting the screening process at airports. The indication of a potential weapon or threat on a person means the screening process has to be temporarily interrupted to remove the person from the screening process for further investigation. Accordingly, if the potential problem or threat is a false alarm, the throughput of the system is unnecessarily interrupted and diminished without providing any benefit in the context of safety to the public. In fact, these false alarms can cause chaos at the busier airports. However, if conventional systems had adequate capability to selectively characterize the above list of items as non-threatening, then public safety and throughput of the screening process is maintained.
Additionally, conventional systems are sensitive to background noise and interference which greatly affects the throughput of the conventional system. For example, due to background noise and interference, conventional systems can indicate a threatening object on a person when no object exists which results in another false alarm. That is, this false alarm is not the result of mischaracterizing an existing object, but the result of an indication that an object exists when it does not. Sources of background noise include wheelchairs, trams, subways and even automobiles that pass proximate, but outside, a screening region of the conventional system. Once an alarm is indicated, whether false or not, only a more thorough investigation can determine if a threatening object exists. In the meantime, the throughput of the system has been interrupted and diminished. More problematic, background noise can interfere with the operability of conventional systems by overwhelming the system to mask the detection of a legitimately threatening object. Furthermore, if the magnitude of the background noise or interference is substantial, the operation of the system can be temporarily suspended or rendered inoperable.
Another form of interference or background noise that needs to be addressed in conventional systems is crosstalk between two or more systems, or crosstalk between respective portals of a single conventional system. Crosstalk results from the close proximity of circuitry and electronic components wherein undesirable communication occurs between the conventional systems or portals and effectively negates or impedes a proper screening process. Conventional structures and methods to address crosstalk include providing physical buffer zones to impede or block the interference. However, the buffer structures increase the area or footprint of a conventional system. In facilities where surface area is at a premium, increasing the footprint of a conventional system may not be an option if any desirably throughput is to be maintained.
Accordingly, there is a need to improve the capabilities of circuitry, systems and methods for detecting magnetic fields. There is a need to improve the capabilities of conventional security screening systems wherein increasing the sensitivity of the system does not affect the selectivity or distinguishing capability of the system thereby maintaining a reasonable throughput. Moreover, there is a need to increase the selectivity or distinguishing capability of the conventional security screening systems. Furthermore, there is a need to improve designs of security screening systems to negate or cancel background noise and interference without increasing the footprint of the system. Making these improvements will increase the capability of security screening systems to detect threatening objects, to distinguish between threatening and non-threatening objects, and to increase throughput, all the while increasing public safety.